Improvement in rock-drilling machines



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@aA-00B HART, or SAVANNAH, MISSOURI.

. Y Leners Para: No, 100,756, dated Match 15, 1870.

` y IMPROVEMENT 1N RoCx-DRILLING MACHINES.

The Schedule referred to in these Letters Patent making part of the sameTo all whom it may concern Be it known that I, JACOB HARTof Savannah, inthe State of Missouri, have invented anew and use.n ful Improvement inRock-Drills and `I do hereby i declarethat the following is a full,clear, and exact description of the same, reference being had to theaccompan ying drawings and lett-ers of reference marked thereon making apart of this specification, in which- 1 Figure 1 is a frontelevation.

This invention consists "n the intel-position of springs, placed around'upwardly-projecting rods, be-

'tweenvthe foot-pietav of the sliding sash and a crossbar of the main7fra1ne,`for the purpose of rendering supptrtin sustaining the slidingsash, and assistance in raising it after it has been oncelowered.

To enable those skilled in theart to make and use my invention, I nowproceed to tion and operationl l Similar letters in the'drawings referto like parts.

A is the frame, and L HH, the foot-blocks, to which the frame isjointed,

describe its construcf the inclination of the former to the latter beingcontrolled by semieircular arr'ns G' and set screws, in a common andwell-known manner.

f The frame A'bears ,on its Ifront ways,and used for rendering thedrills noperativeat pleasure. Y

The sash is connected by a bar, d', with a lever, d, whose fulcrum is atd on the top of the frame A, and whose oflceis to lower the sash, soasto compress force on the drills'.

A rack, da, retains the lever d in the it is lowered.

What I claim as my invention is he combination of the frame A, sash B,rods a', and

place to which Witnesses:

JACOB HART.

`ABRAM DoBBs, i

sidc,f i n suitable R. S. EDWARDS.

placed around rods 11" to each drill, sliding horizontally in `suitableguidethe springs b', and cause them to act with greater springs a, inthe manner and for the purpose explained.,

